The present embodiments relate to computer networks and are more particularly directed to network traffic load balancing in a virtual private network.
Ethernet networks have found favor in many applications in the networking industry for various reasons. For example, Ethernet is a widely used and cost effective medium, with numerous interfaces and speed capability up to the Gbps range. Ethernet networks may be used to form a Metro Ethernet Network (“MEN”), which is generally a publicly accessible network that provides a Metro domain, typically under the control of a single administrator, such as an Internet Service Provider (“ISP”). A MEN is typically used to connect between an access network and a core network. The access network often includes private or end users making connectivity to the network. The core network is used to connect to other Metro Ethernet Networks and it provides primarily a packet switching function.
A MEN typically consists of a number of Provider Edge (“PE”) nodes that are identified and configured for communicating with one another prior to the communication of packet traffic. The PE nodes are connected in a point-to-point manner, that is, each PE node is connected to another PE node in an emulated and bi-directional virtual circuit manner, where each such connection is achieved by a Label Switched Path (“LSP”). An LSP is sometimes informally referred to as a link. Thus, each PE node may communicate to, and receive packets from, an adjacent PE node. Further, along each LSP, between adjacent PE nodes, are often a number of Provider (“P”) nodes. The P nodes maintain no state information and serve primarily a routing function and, thus, are understood not to disturb the point-to-point connection between the PE nodes of the MEN, which are more intelligent devices. Also, traffic is said to hop from node to node, including to/from each intermediate P node. Further, a different number of P nodes may be connected in one communication direction between two adjacent PE nodes as compared to the reverse communication direction between those same two adjacent PE nodes. Lastly, note that PE nodes in the MEN are also coupled, sometimes through an intermediate node, to one or more Customer Edge (“CE”) nodes, where those CE nodes thereby represent the interface between the MEN and an adjacent access network.
With the development of the MEN architecture, there have further evolved additional topologies associated with such a network. Certain types of such overlays are referred to as virtual private networks (“VPN”), and as a key example are implemented as private networks operating over the public global Internet. VPN provides the benefits of a private network such as access to company servers and intranet communications, while users of the VPN also benefit from the low operational costs offered by it because the underlying hardware is provided by the Internet. One type of VPN now being offered is the provider provisioned VPN, or “PP-VPN” (also, “PPVPN”). The PP-VPN is typically offered by an ISP, whereby the ISP assumes various obligations to meet an entity's networking requirements and then implements those requirements into a VPN. In any event, as implemented, the PP-VPN often includes another aspect that pertains to the preferred embodiments that are described later, which is the virtual private local area network service (“VPLS”). A VPLS can be of various forms, such as a hierarchical VPLS, a decoupled VPLS, or others. In any event, a VPLS creates an emulated local area network (“LAN”) segment for a given set of nodes in a MEN. The VPLS delivers an ISO layer 2 broadcast domain that is fully capable of learning and forwarding on Ethernet MAC addresses that is closed to a given set of nodes. Thus, within the VPLS, packets may be broadcast to all nodes on the VPLS. Note also that more than one VPLS may be included in a single MEN and, thus, certain PE nodes of that MEN may be a part of more than one VPLS.
Given the various nodes, attributes, and connectivity described above and known in the art, complexities arise in efficient use of the system resources on the MEN and the VPLS so as to optimally route traffic—such an optimization is often referred to as load balancing, that is, balancing the traffic load on those various resources. Prior art balancing solutions treat the issue as one of consideration for the primary paths on the MEN. In contrast, and as detailed below in connection with the preferred embodiments, a MEN is created in which load balancing is handled as a part of the design that also includes the secondary, or so-called “protection” or “backup” paths of the network. As a result, greater optimization may be achieved in the load balancing, as further detailed below.